Shaft adjustment apparatus and method

Supports: racks – Knockdown – Horizontal rod between uprights

Reexamination Certificate

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Details

C211S204000, C211S207000, C248S412000

Reexamination Certificate

active

06796446

ABSTRACT:

FIELD
The apparatus and methods described herein relate generally to adjustment mechanisms between shafts, and in particular, to adjustment mechanisms between a pair of elongate, tubular shafts.
BACKGROUND
An adjustment mechanism can be used to adjust the relative position between two elongate, tubular shafts. One of the shafts may be at least partially slidable within the other of the shafts, with the adjustment mechanism positioned therebetween selectively engageable to substantially prevent relative sliding between the shafts.
A particular type of adjustment mechanism is used in an adjustable garment rack to permit adjustment of the height of a garment rod relative to a base. A pair of upstanding outer shafts are attached to the base. An inner shaft is slidable within each of the outer shafts. Positioned within the outer shaft and below a bottom end of the inner shaft is a roller. Attached to the bottom end of the inner shaft is a supplemental tube having a ramp integrally formed therewith. A thin rod extends through the inner shaft, connected at one end to the roller and at the other end to a button.
A spring biases the button, along with the attached thin rod, from an upper end of the inner shaft to cause the roller to ride up the ramp. As the roller rides up the ramp, it engages the inner wall of the outer shaft. The friction between the roller, the inner wall of the outer shaft, and the ramp attached to the inner shaft prevents relative movement between the inner shaft and the outer shaft. To allow relative movement between the inner shaft and the outer shaft, the button can be depressed against the biasing force of the spring to move the thin rod downwardly, causing the roller attached to the end of the thin rod opposite the button to ride down the ramp and away from the inner wall of the outer shaft.
Although functional, the garment rack adjustment mechanism described hereinabove disadvantageously tends to bind up, where depression of the button does not consistently result in movement of the roller down the ramp to permit relative sliding between the inner and outer shafts. As the roller and the ramp are positioned entirely within the outer shaft, access thereto when the adjustment mechanism is bound up is difficult.
Several factors cause the garment rack adjustment mechanism described above to bind up. One particular problem is when the thin rod becomes off-center, causing the roller to likewise become off-center on the ramp. The roller comprises two rotating wheel members, one on each side of an axle connected to the thin rod. The thin rod is significantly thinner than the inner diameter of the inner shaft. Thus, because the thin rod is only supported by a constriction at its upper extreme, its lower extreme having the roller attached can significantly move within the inner shaft and cause one of the rotating wheel members to be in greater frictional contact between the inner wall of the outer shaft and the ramp than the other, thereby causing the adjustment mechanism to bind up.
Another particular problem with the garment adjustment mechanism described above is the configuration of the ramp, which both contributes to the binding up of the mechanism and is costly to manufacture. The ramp is a separate tube that is attached to the end of the inner shaft. A portion of the tube is cut away at an inclined angle at one opening thereof, and a flat piece of sheet metal is cut into a curved profile and welded thereto. The piece of sheet metal only partially covers the opening in the supplemental tube, and the thin rod and attached roller project through the uncovered portion of the opening. Not only does such a complicated construction increase the cost of the adjustment mechanism, but it also results in a limited range of movement of the roller along the piece of sheet metal before the thin rod contacts the piece of sheet metal. For example, the roller travels only about 0.25 inches down the ramp, even though the ramp is about 1.25 inches in length, before the contact between the thin rod and the ramp lifts the roller from the ramp. When such contact occurs, the roller may lift off of the ramp and not properly engage both the sidewall of the outer tube and the ramp. Further contributing to the minimal travel of the roller along the ramp before the thin rod lifts it therefrom is the sharp angle of the ramp, which is about 23 degrees. If sufficient force is exerted on the roller to press it back down against the ramp, thereby bending the thin rod against the piece of sheet metal, the friction engagement between the roller, the ramp, and the inner wall of the outer shaft may be greater than desirable, which may result in binding of the mechanism and difficulty an adjusting the relative positions of the inner and outer shafts.
Further, the opening is sized to allow the roller to retreat thereinto, which can undesirably result in the roller becoming lodged within the inner tube. In addition, the entire thin rod can easily be withdrawn from the inner tube, contributing to both assembly and operational difficulties.
Problems with the above-described adjustment mechanism are increased when a pair of garment rack adjustment mechanisms are used, one for each of the pair of outer and inner shafts. When one of the adjustment mechanisms binds up and the other does not, or does so to a lesser degree, one of the pair of shafts slide relative to each other to a different extent that the other of the pair of shafts. This can further result in even more binding, as the skewing of one of the pair of shafts relative to the other of the pair of shafts can add to the likelihood of a bound adjustment mechanism.
SUMMARY
There is provided a new improved method and apparatus for adjusting the relative position between a pair of elongate, tubular shafts using an adjustment mechanism. This is achieved by using a wedge element shiftable between a wedged position wherein relative movement between the pair of shafts is substantially prevented and an unwedged position permitting relative movement between the pair of shafts. In the wedged position, the wedge element is frictionally engaged between a ramp and an inner wall of one of the shafts. An actuator member, having a first end region attached to the wedge element and a second end region opposite therefrom, is operable to shift the wedge element between the wedged and unwedged positions to control the relative movement between the pair of shafts. Binding of the adjustment mechanism may be reduced by supporting the actuator member in more than one location to maintain desirable contact between the wedge element and the ramp and the inner wall of the one of the pair of shafts. Binding of the adjustment mechanism may also be reduced by providing for an increased range of movement of the wedge element along the ramp to prevent undesirable frictional engagement between the actuator member and the ramp. Further, a stop may be provided to substantially maintain the wedge element from unintentionally withdrawing into the inner shaft.
An apparatus is provided for adjusting the relative position between two elongate, tubular shafts. The apparatus includes an outer elongate tubular shaft having a diameter and an inside wall. Also included is an inner elongate tubular shaft having a diameter different from the diameter of the outer shaft in order to permit the inner shaft to be slidably received at least partially within the outer shaft. An adjustment mechanism comprising a wedge element, a ramp, and an actuator member is positioned to allow for adjustments in the relative positioning between the inner and outer shafts. A ramp is positioned within the outer shaft and has an inclined surface. The wedge element is rideable along the inclined surface of the ramp between the wedged position and the unwedged position. The wedge element is moveable between a wedged position, wherein it is disposed in frictional engagement between the inner wall of the outer shaft and the ramp, and an unwedged position generally removed from the inner wall of the outer shaft. The wedg

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